<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>传统布局三等份【响应式】</title>
    <style>
        * {
            box-sizing: border-box;
        }
        .main {
            width: 80%;
            height: 200px;
            margin: 200px auto;
            border: 1px solid pink;
            min-width: 400px;
        }
        .main div {
            padding-left: 100px; /*如果说在原来css老盒子中给padding的话会撑开盒子，所以这时我需要用到css3定义成新盒子的属性 */
            float: left;
            width: 33.33%;
            height: 100%;
        }
        .main div:nth-child(1) {
            background-color: orange; /*由此可见padding的里面的内容也会存在背景 */
            
        }
        .main div:nth-child(2) {
            background-color: blue;
        }
        .main div:nth-child(3) {
            background-color: red;
        }
    </style>
</head>
<body>
    <div class="main">
        <div>1</div>
        <div>2</div>
        <div>3</div>
    </div>
</body>
</html>